Child abuse is a dark and depressing reality in American life, but until now, it's never been clear just how widespread a problem it was. A new study, led by Dr. John Leventhal of Yale University, offers the first comprehensive estimate of serious injuries caused by child abuse in the U.S., and the results are pretty horrifying.

The study, published in the journal Pediatrics, found that nearly 4,600 children in the U.S. were hospitalized for injuries caused by physical abuse in 2006, the most recent year for which data was available. Overall, six out of every 100,000 kids under 18 were hospitalized with injuries that ranged from broken bones and burns to traumatic brain injury. The average hospital stay for these children was one week, and 300 of them ended up dying. That puts the death rate for abuse at 6 percent, which is a far higher death rate than exists for other kinds of injury or medical problem that required hospitalization.

Very young children tended to be the most common victims of abuse. For babies under one, there were 58 cases of hospitalization per 100,000 infants. Sadly, children under one who were covered by Medicaid fared worst of all, with one out of every 753 of those babies ending up in the hospital because of abuse. According to Dr. Leventhal, "Medicaid is just a marker of poverty, and poverty leads to stress."

Stress appears to be a key factor in abuse. There was another smaller study that showed an obvious increase in abusive brain injuries after the financial crisis in 2007, which researchers attributed to added stress on parents. Leventhal said stress disproportionately affects younger kids because they are by nature, more difficult to care for:

They are challenging for some parents to take care of because they cry, it's hard to understand what they want and parents can get frustrated, exhausted and angry.

Of course, they also can't defend themselves or runaway as easily as older children can. A heartbreaking reality, and one Dr. Leventhal thinks we need to address urgently. According to his team, at the rate this study found abuse to be occurring, it's a bigger threat to babies than Sudden Infant Death Syndrome. And, of course, this study only deals with kids who are hospitalized. There are many more children who endure abuse but aren't injured severely enough to require medical attention.

So Dr. Leventhal proposes we act to stop abuse in the same way we've worked to stop SIDS: "We need a national campaign related to child abuse where every parent is reminded that kids can get injured." Another probably even more effective option would be to send public health workers to do home visits with new parents to offer support and advice, a practice that is already common in a lot of European countries.

While that level of intervention sounds costly, the expense to society of caring for the abused is far more substantial. Beyond the obvious personal cost to the children and individual families, the study found that abuse-related hospitalizations ran us about $73.8 million in 2006. And in terms of the overall expense of abuse, the CDC reported that one year's worth of child maltreatment cases costs $124 billion over a lifetime.

But no matter what the cost is, preventing abuse is worth it. Leventhal says, "This is a serious problem that affects young children. We need to figure out a way to help parents do better." We spend so much money educating people on everything from cancer prevention to the dangers of cholesterol, but now that we've got a more accurate picture of the damage abuse is doing across the entire country, there's no excuse for not going after the problem immediately on a national level—especially because the children who are falling victim to this abuse can't advocate for themselves.